Interpretive Summary: Utah juniper bark was tested for abortifacient activity by feeding dry ground bark to pregnant beef cattle with known breed dates. The bark was found to induce abortions in three cows after 4, 5 and 6 days of treatment. The diterpene acid agathic acid was identified as the major labdane acid present in the plant. The induced abortions were identical to that produced upon feeding late term pregnant cattle ponderosa pine needs and/or isocupressic acid. It was therefore concluded that agathic acid is an abortifacient agent in late term pregnant cattle. Utah juniper poses little risk for the cattle industry and we have received no reports of cattle abortions caused by Utah juniper. However, other cedar and juniper species in other locations have been analyzed for the labdane resin acids and are considered a risk to cattle grazing in other areas. Therefore, ranchers should use caution when placing pregnant cattle during late gestation where access to trees or shrubs containing these types of compounds is available. Utah juniper bark and agathic acid may have potential research applications however in studies to further understand the overall pine needle abortion problem in cattle.

Technical Abstract:
Freshly ground Utah juniper (Juniperus osteosperma (Torr.) Little) bark was given via gavage at a dosage of 2.3 kg/cow twice daily to three pregnant cows starting on day 255 of gestation. All three cows aborted the calves after four, five and six days of treatment. A fourth cow was dosed Utah juniper needles and this cow calved early on day 268 of gestation with complications consistent with pine needle abortion. Chemical analysis of Juniperus osteosperma bark identified the major diterpene acid as the labdane acid known as agathic acid. Agathic acid was measured in the bark at a concentration of 1.5% (dry weight basis). Analysis of sera samples obtained from treated cows found detectable quantities of agathic acid, dihydroagathic acid and tetrahydroagathic acid, which are known serum metabolites of the abortifacient compound isocupressic acid. Based on the high incidence of induced abortion and detection of known metabolites in affected animals, the labdane acid known as agathic acid is considered to be an abortifacient compound in late term pregnant cattle.